A variety of treatments have been proposed and evaluated for the treatment of pain, including medications, acupuncture, local electrical stimulation, brain stimulation, and surgery. Psychotherapy, relaxation therapy, biofeedback, and behavior modification have also been employed in attempts to treat pain. Despite the many proposed therapies, pain remains an important and increasingly common medical complaint. Moreover, the root causes of pain are sometimes difficult to determine, and frequently are difficult to treat and control.